Find the Hidden Line-Graph Value

A dot on a line graph can hide its value in plain sight. You might spot the right dot... and STILL get the answer wrong. The secret is not counting squares. It is reading both axes carefully.

Start with the name you have been given. Find it along the horizontal axis at the bottom. Put your finger there, then travel straight UP until you meet the plotted point. Do not begin with the numbers at the side. From the point, travel straight across to the vertical axis. That axis tells you the value. Keep your guide line level - no sliding diagonally towards a nearby number. Bottom axis for the named position. Side axis for the VALUE. Now decode the scale. Suppose zero and ten have one grid line between them. There are two equal intervals, so each interval is worth five. Never assume one square means one unit. Check the labelled numbers, count the INTERVALS, then divide.

Try this eleven-plus question. The graph shows how many pages Aisha read each day. The question asks, how many pages did Aisha read on Thursday? We need one plotted value - nothing about whether the line rises or falls. First, inspect the vertical axis. It is labelled zero, ten, twenty, thirty and forty. There is one smaller grid line between each labelled pair. Ten pages split across two equal intervals gives five pages per interval. Next, find Thursday on the bottom axis. Trace straight up... and stop when you reach Thursday's dot. Be careful: Wednesday's dot is close by, but the question names Thursday, so stay in Thursday's column. Trace across from the dot to the side. It lands on the grid line halfway between twenty and thirty. Each interval is five, so the value is twenty-five. Aisha read TWENTY-FIVE pages on Thursday. Answer found!

Remember: find the named position along the bottom, go up to the point, then go across to the value. Decode the scale before you answer. Bottom, up, across... and you've got it.